Development of serum glycosylated exosomal microRNAs as biomarkers for early diagnosis of lung adenocarcinoma.

Early diagnosis is a major challenge in lung adenocarcinoma (LUAD). Tumor-derived exosomal microRNAs (miRNAs) are promising diagnostic biomarkers, and given the aberrant overexpression of tumor-associated glycans on exosomes, we employed a GlyExo-Capture approach using wheat germ agglutinin (WGA)- and lentil lectin (LCA)-coated magnetic beads to enrich glycosylated exosomes (WGA- and LCA-exosomes) from serum, and then detected exosomal miRNAs in 413 serum samples. Initially, small RNA sequencing was performed on a screening set (n = 30) to obtain candidate WGA-exosomal miRNAs. Moreover, candidate WGA-exosomal miRNAs were identified through RT-qPCR to develop a predictive panel of candidate WGA-exosomal miRNAs combined with candidate LCA-exosomal miRNAs identified in our pilot study via an independent training set (n = 254). Finally, the diagnostic value of the predictive panel for early LUAD was determined through a validation set (n = 129). Results showed that WGA- and LCA-coated magnetic beads effectively enriched glycosylated exosomes from both the conditioned media of LUAD cells and the sera of LUAD patients. Furthermore, a 4-miRNA panel of serum WGA-exosomal miR-199a-3p, miR-222-3p, combined with serum LCA-exosomal miR-486-5p, miR-139-3p, was developed for early diagnosis of LUAD. In the training and validation sets, the area under the curve of the 4-miRNA panel was 0.909 and 0.942, respectively. These findings suggest that the serum glycosylated exosomal 4-miRNA panel developed using the GlyExo-Capture approach may serve as a promising strategy for liquid biopsy-based early detection of LUAD.